/// <summary>
/// Builds the <see cref="CriteriaExpression"/>, and returns an <see cref="Expression"/>.
/// </summary>
/// <typeparam name="T">Type used in the <see cref="Expression{TDelegate}"/>.</typeparam>
/// <param name="criteriaExpression">The <see cref="CriteriaExpression"/>.</param>
/// <returns>The <see cref="Expression{T}"/></returns>
public virtual Expression <Func <T, bool> > Build <T>(CriteriaExpression criteriaExpression)
where T : class
{
if (criteriaExpression == null)
{
throw new ArgumentNullException(nameof(criteriaExpression));
}
var parameter = Expression.Parameter(typeof(T), "x");
var expression = this.BuildExpression(criteriaExpression, parameter);
return(Expression.Lambda <Func <T, bool> >(expression ?? Expression.Constant(true), parameter));
}
/// <summary>
/// Builds the <see cref="CriteriaExpression"/>'s, and returns an <see cref="Expression"/>.
/// </summary>
/// <typeparam name="T">Type used in the <see cref="Expression{TDelegate}"/>.</typeparam>
/// <param name="criteriaExpression">The <see cref="CriteriaExpression"/>.</param>
/// <returns>The <see cref="Expression{T}"/></returns>
public virtual Expression <Func <T, bool> > Build <T>(CriteriaExpression criteriaExpression)
where T : class
{
if (criteriaExpression == null)
{
throw new ArgumentNullException(nameof(criteriaExpression));
}
var logicalType = LogicalType.And;
var parameter = Expression.Parameter(typeof(T), "x");
Expression expression = null;
foreach (var statement in criteriaExpression.Criterias)
{
Expression innerExpression;
if (statement.Property.Contains("[") && statement.Property.Contains("]"))
{
var baseName = statement.Property.Substring(0, statement.Property.IndexOf("[", StringComparison.Ordinal));
var name = statement.Property.Replace(baseName, "").Replace("[", "").Replace("]", "");
var type = parameter.Type.GetRuntimeProperty(baseName).PropertyType.GenericTypeArguments[0];
var method = typeof(Enumerable).GetRuntimeMethods().First(m => m.Name == "Any" && m.GetParameters().Length == 2).MakeGenericMethod(type);
var member = this.GetMember(parameter, baseName);
var parameter2 = Expression.Parameter(type, "i");
var expr2 = Expression.Lambda(this.GetExpression(parameter2, statement, name), parameter2);
innerExpression = Expression.Call(method, member, expr2);
}
else
{
innerExpression = this.GetExpression(parameter, statement);
}
expression = expression == null
? innerExpression
: logicalType == LogicalType.And
? Expression.AndAlso(expression, innerExpression)
: Expression.OrElse(expression, innerExpression);
logicalType = statement.LogicalType;
}
return(Expression.Lambda <Func <T, bool> >(expression ?? Expression.Constant(true), parameter));
}
private Expression BuildExpression(CriteriaExpression criteriaExpression, Expression parameter)
{
var prevLogicalType = LogicalType.And;
Expression expression = null;
foreach (var criteria in criteriaExpression.Criterias)
{
Expression innerExpression;
if (criteria.Property.Contains("[") && criteria.Property.Contains("]"))
{
var baseName = criteria.Property.Substring(0, criteria.Property.IndexOf("[", StringComparison.Ordinal));
var name = criteria.Property.Replace(baseName, "").Replace("[", "").Replace("]", "");
var type = parameter.Type.GetRuntimeProperty(baseName).PropertyType.GenericTypeArguments[0];
var method = typeof(Enumerable).GetRuntimeMethods().First(x => x.Name == "Any" && x.GetParameters().Length == 2).MakeGenericMethod(type);
var member = this.GetMember(parameter, baseName);
var parameter2 = Expression.Parameter(type, "i");
var expr2 = Expression.Lambda(this.GetExpression(parameter2, criteria, name), parameter2);
innerExpression = Expression.Call(method, member, expr2);
}
else
{
innerExpression = this.GetExpression(parameter, criteria);
}
expression = expression == null
? innerExpression
: prevLogicalType == LogicalType.And
? Expression.AndAlso(expression, innerExpression)
: Expression.OrElse(expression, innerExpression);
prevLogicalType = criteria.LogicalType;
}
return(expression);
}
